Content area
Full Text
Passage of small amounts of blood in diarrheal stools (hematochezia) may sometimes arise from hemorrhoids or from mucosal tears which are a consequence of the spasm, hypermotility or mechanical irritation at the mucocutaneous junction, irrespective of the underlying cause of the diarrhea. However, persistence of hematochezia is always significant of an infectious or inflammatory cause of diarrhea. In the pediatric patient, bloody diarrhea is most often due to an infectious enteric pathogen. Clues to the identification of the specific agent involved in the disease process may be gleaned from a combination of history taking, physical examination and simple laboratory studies (Table). However, the definitive diagnosis will depend upon the results of bacteriologie or viral cultures, and examinations for pathogenic protozoa, the presence of specific toxins and sometimes on serology titers. The decision to culture the stool specimen can be made after examining the material (preferably the mucopus) for the presence of white blood cells either by methylene blue or Wright's stain, as well as for blood. l If positive, a darkfield or modified Gram's stain examination should be performed to search for organisms resembling Campylobacter and a wet mount preparation examined for amoeba.2 In the presence of diarrhea, stool containing either blood or white blood cells should be sent for bacteriologie culture. Screening the sample for toxin or ova and parasites can be decided upon if the history reveals recent exposure to antibiotics or travel to or from endemic areas of the world.
Endoscopic evaluation of the colon including histologic examination of mucosal biopsy specimens can generally be delayed until laboratory results are available since they add little specific diagnostic information, especially when performed early in the illness. The histologic findings can help, however, in differentiating antibiotic-associated colitis and acute self-limited colitis from idiopathic inflammatory bowel disease.3
Up until 5 to 10 years ago, dysenteric symptoms (abdominal pain, tenesmus, small volume bloody stools) were attributed to shigella, salmonella or amebiasis. Now the list of enteric pathogens responsible for dysenteric disease includes Campylobacter, Yet' sinia, Clostridium difficile, both enteroinvasive and enteropathogenic E. coli, gonococcus, Chlamydia tra' chomatis, and Herpes simplex. Conditions such as necrotizing enterocolitis, allergic colitis, idiopathic inflammatory bowel disease and hemolytic-uremicassociated colitis will be included in the differential diagnosis at least until the results...